getTag

expectsArguments

boolean expectsArguments()

Return true if this extension expects arguments to act on. Some
extensions may not need arguments; for example, an extension to
switch a string to upper case might be of the form:
field.ext:toUpperCase ().

expectsTarget

boolean expectsTarget()

Return true if this extension expects a target to act on. Some
extensions act on a field or object value; others stand alone.
field.ext:toUpperCase () acts on the target
field but has no arguments, while another possible form,
ext:toUpperCase (field) has no target but does have an
argument.